Many communication cables are now buried into the ground. In such applications, the communication cable needs to withstand water penetration into the cable because water can severely affect the performance of the cable. For example, in an electrical cable, water destroys the capacitance balance of the electrical conductor. In an optical cable, water can negatively affect the integrity of the optical cable.
One solution devised by those skilled in the art to minimize water penetration into the cable involves pressurizing the interior of the cable with dry air. While the pressurized dry air cable may be useful in stopping water migration into the cable, it proves to be expensive to maintain and is not a widely accepted solution for cables buried under ground.
Another, more widely practiced solution involves filing the interior interstitial space of a cable with a water insoluble filling material, such as a sealant, that would plug the cable and stop the migration of water. When a filling material is used, several factors are usually taken into consideration, such as, e.g., its dielectric constant, density, aging and temperature stability, hydrophobic nature of the composition, processing and handling characteristics, shrinkage of the filling material upon cooling, toxicity, and cost.
While the foregoing technology may be useful, there exists a need for different filling materials with lower dielectric constants while taking into consideration the factors listed in the preceding paragraph.